Filament support for incandescent electric lamps



P 1969 J. s. CARDWELL, JR 3,441,776

FILAMENT SUPPORT FOR INGANDESCENT ELECTRIC LAMPS Filed May 12, 1967lnvenfitor": John G. Car'dwetl dr. 109 0x2; JZ

His A't to e9 United States Patent Office 3,441,776 Patented Apr. 29,1969 US. Cl. 313-273 2 Claims ABSTRACT OF THE DISCLOSURE In asingle-ended incandescent electric lamp, particularly of the highintensity halogen regenerative cycle type, comprising a sealed envelopeof vitreous material containing a coiled filament and having a pinchseal at one end and a pair of lead-in conductors having portions thereofhermetically sealed in said pinch seal, the coiled filament is composedof sections which extend in generally side-by-side relationlongitudinally of the envelope with their lower ends electricallyconnected to the lead-in conductors. The sections of the filament arephysically separate segments, and their upper ends are supported by, andelectrically connected together by, a support member preferably in theshape of an inverted double-J consisting of a length of wire formed asI-shaped wire sections arranged back-to-back. The stem portion of thedouble-J extends longitudinally between the filament segments, has itslower end embedded in the pinch seal, and has its upper hookshaped endsfitted or threaded a supporting mandrels Within the interior ofrespective helically coiled upper end portions of the respectivefilament sections.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates generally to electric incandescent lamps comprising a sealedbulb or envelope containing a filament, and more particularly to afilament support structure.

Description of the prior art The invention relates more particularly tolamps of a single-ended type comprising a sealed envelope having a pinchseal at one end thereof, a pair of lead-in conductors having portionsthereof hermetically sealed in said pinch seal, and a coiled filamentformed to provide sections which extend in generally side-by-siderelation, for example a generally U-shaped or V-shaped filament havingits ends supported from the pinch seal and electrically connected torespective lead-in conductors. Still more par ticularly, the inventionrelates to such lamps wherein it is required that the filament beprovided with supplemental support means at its midpoint or apex. Insome such cases the support has been provided by a wire having one endlooped about the filament and its other end secured or sealed in anexhaust tip at the end of the envelope opposite the pinch seal. Inanother case the support wire was in the form of an inverted hairpin orU having its ends embedded in the pinch seal and having a loop at itsbend enclosing the filament at its apex. Such prior art structurespresent certain problems in difficulty of assembly and proper locationor orientation of the support members and filaments.

SUMMARY OF THE INVENTION In accordance with the present invention, thefilament is formed of physically separate sections, and the support wiremember is formed to provide a stem portion having one end thereof sealedin the pinch seal between the lead-in conductors and extending therefromlongitudinally into the interior of the envelope where it terminates inbranches extending short distances laterally of the stem portion inopposite directions. The separate filament sec tions are arranged toextend generally longitudinally of the envelope at opposite sides of thestem portion of the support member with helically coiled end portionsthereof threaded over respective said branches as supporting mandrelstherefor; the opposite ends of the filament are electrically connectedto respective lead-in conductors. In a preferred form, the supportmember is of generally doubleshape formed of a length of wire which isdoubled back upon itself to constitute the stem portion and which hasits free ends formed as hooks arranged in back-to-back relation in acommon plane. Such an arrangement of filament and support member isreadily assembled with the parts in proper relationship, as will moreclearly appear from the following detailed description and from thedrawing.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is an elevation of a lamp comprising the invention;

FIG. 2 is an exploded elevation, on an enlarged scale, showing the partsof the filament and support members prior to assembly;

FIG, 3 is an exploded elevation showing the filament and support wireelements in assembled relationship, and a pair of lead-in conductorsprior to assembly with the filament;

FIG. 4 is an elevation showing the assembly of the complete filamentmount structure held in a supporting fixture, and a bulb or envelopeheld in enclosing relationship to the filament mount for sealingthereto;

FIG. 5 is a top view of the assembly of filament and support wiremembers shown in FIG. 3;

FIG. 6 is a section through the pinch seal along the line 6-6 in FIG. 1;

FIGS. 7, 8 and 9 are elevations of modified embodiments or species ofthe filament support wire member;

and

FIG. 10 is a top view of the species of support member shown in FIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 of thedrawing, the lamp illustrated therein is of a high intensityregenerative cycle type comprising a compact bulb or envelope 1 ofvitreous material of high melting point, preferably essentially fusedsilica, having at one end thereof a flattened pinch seal 2 which may beof known I-shaped cross section (FIG. 6) and into which extend a pair oflead-in conductors 3 having thin foil portions 4, preferably ofmolybdenum, hermetically sealed in the pinch seal 2. The envelope 1contains a filament, preferably of tungsten, formed to provide sections5 which extend in generally side-by-side relation with their lower endssupported from the pinch seal 2 and electrically connected to respectivelead-in conductors 3, 4. The upper ends of the filament sections 5 aresupported by a support wire member 6 which has its lower end embeddedand anchored in the pinch seal 2. The envelope 1 also contains a fillingof inert gas, such as nitrogen, argon, krypton or xenon and a quantityof halogen, such as iodine or bromine preferably in the form of acompound such as hydrogen bromide or a hydrocarbon of bromide, whichfunctions in known manner as a regenerative getter to return vaporizedtungsten to the filament.

In accordance with the invention, as shown in FIG. 2, the filamentsections 5 are made as physically separate segments. In this case, eachsegment is in the form of a helically coiled-coil having upper and lowersingle coiled end legs 7 and 8 which extend longitudinally therefrom.The legs 7 and 8 are preferably in longitudinal alignment and extendfrom the edges of the cylinders defined by the respective coiled-coilbody portions of the filament 5. The support member 6 is preferably ofgenerally double-J shape formed of a single length of wire, preferablytungsten, which is doubled back upon itself to constitute a stem portion9 and which has its free ends formed as hooks 10 which extend laterallyof the stem portion 9 in opposite directions to be in a common plane.Preferably, there are also provided a pair of spuds or inner lead wiresections 11 which are fitted as mandrels into the interior of the lowerfilament legs 8.

As shown in FIG. 3, the filament sections are assembled with the supportmember 6 by threading or fitting the leg portions 7 of the filament overrespective hooks as supporting mandrels. The assembled is preferablyarranged as shown in FIG. 5 so that the stem 9, hooks 10 and the axes 12of the coiled-coil filaments 5 lie in a common plane, with the said axes12 at the outside of the hooks 10. Also shown in FIG. 3 is the remainderof the mount structure consisting of the outer lead wires 3 and foilportions 4 of the lead-in conductors.

As shown in FIG. 4, the outer lead wires 3, carrying the foils 4, areinserted in elongated holes or bores in a supporting block or fixture 13where they may be securely held by any suitable frictional arrangementwhich is herein illustrated as a pair of screws 14, and the ends of thelower filament legs 8, with spuds 11 (FIG. 2) held therein, are weldedto respective foils 4, preferably through the intermediary of a tab 15of suitable metal, such as platinum-coated molybdenum, which serves toimprove the strength of the weld between the molybde num foil 4 and thetungsten filament leg 8 and spud 11. The stem portion 9 of the supportmember 6 is quite firmly held in parallel alignment with and between thefilament coil sections 5.

As also shown in FIG. 4, the filament mount is enclosed within a bulb orenvelope 1 which may be of generally spherical shape with a cylindricalneck portion 17 enclosing the foils 4 and adjacent portions of thefilament legs 8 and outer lead wires 3. The bulb is also provided with atubulation 18 which may be engaged by a pair of jaws indicated at 19, tosupport the envelope in proper sealing relation to the filament mountstructure. The said neck portion 17 of the bulb is then heated to aplastic condition and pinched by a pair of jaws in known manner to formthe flattened pinch seal 2 (FIGS. 1 and 6) in which the foils 4 arehermetically sealed and the lower end of the stem portion 9 of thesupport wire member 6 is sealed and anchored to thereafter firmlysupport the filament sections 5 at their upper ends.

The bulb 1 is then exhausted or purged of air and filled with an inertgas and a quantity of halogen as well known in the art, and the exhausttube 18 is sealed or tipped olf as illustrated in FIG. 1.

By way of example only, a lamp as described above may be made to have arating of some 650 watts at 220 volts in a bulb 1 of essentially fusedsilica, such as quartz glass or the 96% silica product known as Vycor,and having a diameter of approximately inch, and containing about 800torr of nitrogen with about 2% by volume of hydrogen bromide.

The modified support wire member 6a shown in FIG.

7 is essentially like that described above and shown in FIGS. 1 to 5. Inthis case the stem portion 9a is a single length of wire having one ofthe hooks 10a formed at its upper end, the other hook 10a being formedof a separate piece of wire which is suitably secured, as by welding, tothe main stem portion 9a.

In FIG. 8, the support member 6b is of T-shape comprising an elongatedstem portion 9b which has welded to its upper end a cross piece formingthe opposed branches 10b onto which are threaded the leg portions 7b ofthe filament sections 5b.

The species of support wire member 66 shown in FIGS. 9 and 10 has a stemportion and hook portions like those described above and shown in FIGS.1 to 5, but the hooks 10c terminate in lateral extensions 20 which carrypigtail loops 21 each of which is formed as a partial turn of a helixhaving a diameter and pitch corresponding to part of one secondary coilturn of the coiledcoil filament sections 50. In this case the filamentlegs 7 of FIG. 2 are omitted, and the primary coiling of part of theuppermost secondary turn of each of the filament sections 50 is threadedover the loop 21 which serves as a supporting mandrel.

What I claim as new and desire to secure by letters Patent of the UnitedStates is:

1. An electric incandescent lamp of the halogen regenerative cycle typecomprising a compact sealed envelope of essentially fused silica havinga pinch seal at one end, a pair of lead-in conductors extending intosaid pinch seal from the exterior thereof and including thin foilportions hermetically sealed therein, a filament support wire member ofgenerally double-J shape formed of a length of wire which is doubledback upon itself to constitute a stem portion and which has its freeends formed as hooks arranged back-to-back, said stem portion having itsclosed end sealed in said pinch seal between said leadin conductors andextending therefrom longitudinally into the interior of said envelope, afilament composed of physically separate helically coiled-coil sectionswhich extend longitudinally of the envelope at opposite sides of thestem portion of said support wire member and which have proximate endsterminating in helically single-coiled legs which are threaded over andsnugly enclose respective said hooks as supporting mandrels therefor,and means electrically connecting the opposite ends of said filamentsections to respective said lead-in conductors.

2. A lamp as set forth in claim 1 wherein said coiled legs extend fromthe edges of cylinders defined by respective said coiled-coil sections,and said hooks along with the axes of said coiled-coil sections lie in acommon plane, with said axes at the outside of said hooks.

References Cited UNITED STATES PATENTS 2,007,922 7/1935 Braselton313-273 X 2,007,933 7/ 1935 Braselton 313-344 X 3,194,999 7/1965Heinlein 313-273 X 3,270,238 8/1966 Mosby 313-279 JAMES W. LAWRENCE,Primary Examiner.

R. F. HOSSFELD, Assistant Examiner.

U.S. C1. X.R. 313-222, 279, 344

